1. Field of the Invention
When light outputted from an optical fiber connector is measured by a photodetector, a photoreceptacle capable of connecting to the optical fiber connector is mounted on the photodetector. The present invention relates to such a photoreceptacle for measuring light.
2. Prior Art
A structure of a conventional photoreceptacle will be described next with reference to FIG. 2. In FIG. 2, denoted by 1 is a photodetector, 7 is a receptacle, 8 is an adaptor, 9 is a stopper, 11 is a holder, and 12 is an optical fiber connector.
In FIG. 2, photodetector elements are incorporated in the center of the cylindrical photodetector 1. The holder 11 is secured to the photodetector 1 at its light receiving side. The photoreceptacle 7 is secured to the holder 11. The adaptor 8 is secured to the photoreceptacle 7.
The photoreceptacle 7 has a hole 7A at the center thereof into which a ferrule 12A of the optical fiber connector 12 is inserted. The hole 7A has a stepped portion at the end to which the stopper 9 is secured. The stopper 9 has a throughhole at the center through which light passes.
FIG. 2 shows a view showing a state where the optical fiber connector 12 is connected to the photoreceptacle 7. In FIG. 2, the end of the ferrule 12A is inserted into the hole 7a until it contacts the stopper 9. In FIG. 2, the ferrule 12A is inserted in the hole 7A of the photoreceptacle 7, while the cylindrical part of the adaptor 8 is inserted into a hole of a plug 12B, so that the optical fiber connector 12 is connected with the photoreceptacle 7.
In FIG. 2, the inner diameter of the hole 7A of the photoreceptacle 7 is greater than the maximum limit of the outer diameter of the ferrule 12A. Accordingly, there are cases where the optical fiber connector 12 and the photoreceptacle 7 are unstably connected with each other. In case of FIG. 2, if the shape of the plug 12B is different, a different adaptor 8 corresponding to the shape of the plug 12B must be prepared even when the outer diameter of the ferrule 12A is the same as the inner diameter of the hole 7A of the photoreceptacle 7.
Further, there is a problem that the photoreceptacle in a parallel arrangement such as "the two-core optical fiber connector" or "the F08 type two-core optical fiber connector", respectively stipulated by JIS C5976 or C5977, or the FDDI type optical fiber connector, cannot be used commonly with the photoreceptacle in the arrangement shown in FIG. 2 although the shape of the ferrule is the same.